Rotation shaft seal

ABSTRACT

A rotating shaft seal provided with a seal element, arranged between a housing and a rotation shaft, which contacts the rotation shaft, and a seal member made of rubber having a lip end portion, disposed on a fluid storing chamber side to the seal element, which contacts the rotation shaft, comprising a supporting metal for supporting a rear face of the seal member of rubber.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to a rotation shaft seal, especially, arotation shaft seal used for sealing high pressure fluid in a compressorfor an air conditioner on an automobile.

[0003] 2. Description of the Related Art

[0004] As a conventional rotation shaft seal of this kind, a shaft sealas shown in FIG. 41 is known. This rotation shaft seal is disposedbetween a housing 31 such as a case of a compressor and a rotation shaft32 for sealing fluid or gas in a fluid storing chamber 33.

[0005] In the construction of the shaft seal, a seal member 35 made ofrubber is adhered to an outer case 34, and a first seal element 36 and asecond seal element 37 made of synthetic resin (such as PTFE) havingspiral grooves are unified with a first inner case 38, a washer 39, asecond inner case 40, etc. in the outer case 34 (by caulking).

[0006] The seal member 35 made of rubber is provided with a lip portion42 protruding to the fluid storing chamber 33 side, the lip portion 42has a concave portion 44 in a peripheral direction on the fluid storingchamber 33 side and a lip end portion 41 gradually diminishes indiameter to the fluid storing chamber 33 side, and, a tip of the lip endportion 41 contacts the rotation shaft 32 as to make a belt contact areato seal. That is to say, when the shaft is still, fluid is completelysealed by pressure of the fluid storing chamber 33 and elastic force ofthe lip end portion 41 itself.

[0007] And, when the rotation shaft 32 rotates, although slight leakageis generated in a sliding portion of the lip end portion 41 and therotation shaft 32, the leakage is pushed back (to the left side in FIG.41) by hydrodynamic effect of the spiral grooves (screw threads) of thefirst seal element 36 and the second seal element 37. The constructioncan seal the fluid as a whole.

[0008] To describe concretely, as shown in FIG. 42A, in the seal member35 made of rubber in a non-attached state to the rotation shaft 32 (freestate), an interference G is arranged on the lip end portion 41 to forman interference portion 46 inner to the periphery of the rotation shaft32. And, as shown in FIG. 42B, in the seal member 35 attached to therotation shaft 32, tightening force F₁₁ generated by elasticity ofrubber works on a contact portion 43 (with the rotation shaft 32) of thelip end portion 41 (the interference portion 46) to a peripheral face ofthe rotation shaft 32. And, as shown in FIG. 42C, in the seal member 35pressurized (by pressure P of the fluid) in a pressurizing state of thefluid storing chamber 33, self-sealing force F₁₂ (generated bypressurization) and the tightening force F₁₁ (working continuously) workon the contact portion 43. Consequently, total force F₁₅ (=F₁₁+F₁₂)works on the contact portion 43 to the peripheral face of the rotationshaft 32.

[0009] In the conventional seal described above, in case that thepressure in the fluid storing chamber 33 is high, the lip end portion 41contacts the rotation shaft 32 with a large area for great deformation(by high pressure working in an arrow P direction in FIG. 42C),sealability becomes unstable, and sealability of the first seal element36 is also influenced. This causes problems that leakage is generatedearly, and abrasion of the contact portion of the lip end portion 41with the rotation shaft 32 is large.

[0010] Further, root of the lip portion 42 has larger pressure receivingarea and smaller amount of rubber (in comparison with other parts of thelip portion 42) for the concave portion 44. Therefore, fissures on theroot of the lip portion 42 and exfoliation of the seal member 35 fromthe outer case 34 are generated because the root of the lip portion 42is greatly deformed by the high pressure and stress is successivelygenerated from the surface of the lip portion 42 to the outer case 34.Further, there is a problem that the contact portion of the lip endportion 41 with the rotation shaft 32 becomes larger, and lifetime ofthe seal is shortened.

[0011] Further, in case that carbon dioxide, having high permeabilityagainst rubber and resin, is used as a cooling medium, carbon dioxidepermeates the seal member 35 made of rubber, the first seal element 36,and the second seal element 37 and leaks from the seal. That is to say,when leakage of the cooling medium is large, the cooling medium becomesshort early, and inconvenience such as reduction of cooling effect forshortage of cooling medium is caused thereby.

[0012] It is therefore an object of the present invention to provide arotation shaft seal used especially under high pressure (around 3 to 10MPa, for use of high pressure cooling media such as CO₂), with whichleakage of the cooling medium is restricted, deformation of the lip endportion is small, the lip end portion has good durability for preventionof early abrasion, and sealability is stable with the contact areaprevented from being enlarged.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The present invention will be described with reference to theaccompanying drawings in which:

[0014]FIG. 1 is a half front view showing a first preferred embodimentof the present invention;

[0015]FIG. 2A is an enlarged cross-sectional view of a principalportion;

[0016]FIG. 2B is an enlarged cross-sectional view of a principalportion;

[0017]FIG. 3 is an enlarged cross-sectional view showing a comparisonexample;

[0018]FIG. 4 is a half front view showing a modification of the firstpreferred embodiment;

[0019]FIG. 5 is an enlarged cross-sectional view of a principal portion;

[0020]FIG. 6 is a half front view showing a second preferred embodimentof the present invention;

[0021]FIG. 7A is an enlarged cross-sectional view of a principalportion;

[0022]FIG. 7B is an enlarged cross-sectional view of a principalportion;

[0023]FIG. 8 is a half front view showing a modification of the secondpreferred embodiment;

[0024]FIG. 9A is an enlarged cross-sectional view of a principalportion;

[0025]FIG. 9B is an enlarged cross-sectional view of a principalportion;

[0026]FIG. 10 is a half front view showing another modification of thesecond preferred embodiment;

[0027]FIG. 11 is an enlarged cross-sectional view of a principalportion;

[0028]FIG. 12A is a cross-sectional view of a principal portion showinga modification of a reinforcing cover metal;

[0029]FIG. 12B is a cross-sectional view of a principal portion showinga modification of a reinforcing cover metal;

[0030]FIG. 13 is a half front view showing a third preferred embodimentof the present invention;

[0031]FIG. 14A is an enlarged cross-sectional view of a principalportion;

[0032]FIG. 14B is an enlarged cross-sectional view of a principalportion;

[0033]FIG. 15 is a half front view showing a modification of the thirdpreferred embodiment;

[0034]FIG. 16A is a working explanatory view of a principal portion;

[0035]FIG. 16B is a working explanatory view of a principal portion;

[0036]FIG. 17A is a working explanatory view of a principal portion;

[0037]FIG. 17B is a working explanatory view of a principal portion;

[0038]FIG. 18 is a half front view showing a modification of the thirdpreferred embodiment;

[0039]FIG. 19 is an enlarged cross-sectional view of a principalportion;

[0040]FIG. 20A is a cross-sectional view of a principal portion showinganother modification of the third preferred embodiment;

[0041]FIG. 20B is a cross-sectional view of a principal portion showinganother modification of the third preferred embodiment;

[0042]FIG. 20C is a cross-sectional view of a principal portion showinganother modification of the third preferred embodiment;

[0043]FIG. 20D is a cross-sectional view of a principal portion showinganother modification of the third preferred embodiment;

[0044]FIG. 21A is a working explanatory view of a principal portionshowing still another modification of the third preferred embodiment;

[0045]FIG. 21B is a working explanatory view of a principal portionshowing still another modification of the third preferred embodiment;

[0046]FIG. 22A is a working explanatory view of a principal portion;

[0047]FIG. 22B is a working explanatory view of a principal portion;

[0048]FIG. 23A is a cross-sectional view of a principal portion showinga further modification of the third preferred embodiment;

[0049]FIG. 23B is a cross-sectional view of a principal portion showinga further modification of the third preferred embodiment;

[0050]FIG. 24 is a half front view showing a fourth preferred embodimentof the present invention;

[0051]FIG. 25A is an enlarged cross-sectional view of a principalportion;

[0052]FIG. 25B is an enlarged cross-sectional view of a principalportion;

[0053]FIG. 26 is an enlarged cross-sectional view of a principal portionshowing a modification of the fourth preferred embodiment;

[0054]FIG. 27A is a working explanatory view of a principal portion;

[0055]FIG. 27B is a working explanatory view of a principal portion;

[0056]FIG. 28 is a half front view showing another modification of thefourth preferred embodiment;

[0057]FIG. 29 is an enlarged cross-sectional view of a principalportion;

[0058]FIG. 30A is a working-explanatory view of a principal portionshowing a still another modification of the fourth preferred embodiment;

[0059]FIG. 30B is a working-explanatory view of a principal portionshowing a still another modification of the fourth preferred embodiment;

[0060]FIG. 31 is a partial cross-sectional side view showing a fifthpreferred embodiment of the present invention;

[0061]FIG. 32 is a partial cross-sectional side view showing apre-attachment state;

[0062]FIG. 33 is a graph showing effect of the seal;

[0063]FIG. 34 is a partial cross-sectional side view showing a firstmodification of the fifth preferred embodiment;

[0064]FIG. 35 is a partial break side view showing a second modificationof the fifth preferred embodiment;

[0065]FIG. 36 is a partial break side view showing a third modificationof the fifth preferred embodiment;

[0066]FIG. 37 is a partial cross-sectional side view showing a fourthmodification of the fifth preferred embodiment;

[0067]FIG. 38 is a partial cross-sectional side view showing a fifthmodification of the fifth preferred embodiment;

[0068]FIG. 39 is a partial cross-sectional side view showing a sixthmodification of the fifth preferred embodiment;

[0069]FIG. 40 is a partial cross-sectional side view showing a seventhmodification of the fifth preferred embodiment;

[0070]FIG. 41 is a half front view of a conventional example;

[0071]FIG. 42A is a working explanatory view of a principal portion ofthe conventional example;

[0072]FIG. 42B is a working explanatory view of a principal portion ofthe conventional example; and

[0073]FIG. 42C is a working explanatory view of a principal portion ofthe conventional example.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0074] Preferred embodiments of the present invention will now bedescribed with reference to the accompanying drawings.

[0075]FIG. 1 through FIG. 5 show a first preferred embodiment of arotation shaft seal relating to the present invention, which is used fora compressor of air conditioner for automobiles in which a high pressurecooling medium (such as CO₂) works on a fluid storing chamber 33 side.

[0076] That is to say, this rotation shaft seal is disposed between ahousing 31 such as a case of the compressor and a rotation shaft 32 (onits peripheral face) to seal fluid such as high pressure cooling medium.

[0077] To explain the construction concretely, as shown in FIG. 1, theshaft seal is composed of an outer case 1 made of metal having innerbrim portions 2 and 3, a seal member 5 made of rubber fixed to andunified with a peripheral face of a cylinder portion 4 of the outer case1 and both sides of the inner brim portion 2 by adhesion, welding,baking, etc., a seal element E, a first inner case 9, a washer 10, asecond inner case 11, and a supporting metal 12. And, in FIG. 1, theseal element E is composed of a first seal element 7 and a second sealelement 8 having spiral grooves 6.

[0078] The seal member 5 made of rubber is composed of a cylindricalcover portion 5 a of which peripheral face is formed to be undulate (ina free state) to elastically contact an inner peripheral face of thehousing 31 for seal working, an inner brim cover portion 5 b of whichcross section is U-shaped covering both sides of the inner brim portion2, and a lip portion 13 protruding from an inner side of the inner brimcover portion 5 b of which cross section is U-shaped to the fluidstoring chamber 33 side.

[0079] The lip portion 13 is composed of a short cylinder portion 13 a,and a lip end portion 13 b which diminishes in diameter gradually to thefluid storing chamber side. And, the lip portion 13 of approximatelyuniform thickness has a configuration bent in cross section (as shown inFIG. 1). A tip end portion 14 of the lip end portion 13 b, linearlycontacts the peripheral face of the rotation shaft 32 to seal in anattached (used) state.

[0080] The supporting metal 12 is disposed between the first sealelement 7 and the seal member 5 made of rubber as to adhere to a sideportion opposite to the fluid storing chamber 33 or an inner portion ofthe inner brim cover portion 5 b of the seal member 5, the shortcylinder portion 13 a, and a the lip end portion 13 b.

[0081] As shown in FIG. 1 and FIG. 2, the lip end portion 13 b has aninclination angle of 10° to 45° to an axis L of the rotation shaft 32,and the supporting metal 12, as to correspond to the lip end portion 13b, has a slope receiving face A on its end as to have an inclinationangleθ of 10° to 45° to the axis L.

[0082] Concretely, the supporting metal 12, of which cross section isapproximately L-shaped, is composed of a flat board portion 15 at rightangles with the axis L, and a cylinder portion 16 of short cylinder ofwhich center is the axis L. An end portion 16 a (on the fluid storingchamber 33 side) of the cylinder portion 16 is bent with the aboveinclination angles at a bent portion 17 as to diminish in diametergradually to the end, and a peripheral face of the end portion 16 aforms the former-mentioned slope receiving face A.

[0083] The bent portion 17 corresponds and tightly fits to the shortcylinder portion 13 a of the seal member 5 and a bent inner corner ofthe lip end portion 13 b. And, as shown in FIG. 2B, it is preferable toform an R-shaped chamfer 20 on an end corner portion of the slopereceiving face A of the supporting metal 12. That is to say, an endcorner portion of the supporting metal 12 is effectively prevented frombiting into the lip end portion 13 b of the lip portion 13 to causefissures in the lip end portion 13 b.

[0084] And, as shown in FIG. 1, the outer case 1 is unified with theseal member 5 of rubber by adhesion, etc. beforehand. The supportingmetal 12, the first seal element 7, the first inner case 9, the washer10, the second seal element 8, and the second inner case 11 are seriallyfitted to the outer case 1 in a straight state (a cylindrical state) inwhich the inner brim portion 3 is not formed. Then, the inner brimportion 3 is formed by caulking and the all parts are unified.

[0085] The supporting metal 12, the first inner case 9, the second innercase 11, the washer 10, and the outer case 1 are made of metal such assteel. The first seal element 7 and the second seal element 8 are madeof fluororesin such as PTFE. Further, the seal member 5 is, consideringcooling medium resistance, made of HNBR of which JIS hardness ispreferably set to be 87 to 96 (by composition of HNBR) to preventdeformation when the seal receives pressure. The seal member is greatlydeformed when the JIS hardness is lower than 87, and slightly poor inelasticity when the JIS hardness is higher than 96.

[0086] Although sealing function is similar to that of theformer-described conventional example, the lip end portion 13 b isreceived (supported) by the slope receiving face A of the supportingmetal 12 from a reverse side (inner side) and prevented from beingdeformed when pressure P works on the lip end portion 13 b on the fluidstoring chamber 33 side (as shown in FIG. 2), and good sealability ofthe lip end portion 13 b is kept under high pressure.

[0087]FIG. 3 shows a comparison example proposed in conventional oilseals, in which a backup ring 45 is applied to holding of a lip portion13 of a seal member 5 of rubber, disclosed by Japanese Utility ModelPublication No. 2-47311. That is to say, although the backup ring 45 canbackup (hold) a short cylinder portion 13 a of the lip portion 13, isnot useful for prevention of deformation when the lip end portionreceives pressure because an end 45 a of the backup ring 45 is bent for90° and extremely short.

[0088] In short, in the present invention, the slope receiving face A ofwhich inclination angleθ of 10°≦θ≦45° to the axis L is formed on thesupporting metal 12 to approximately correspond to the inclination angleof the lip end portion 13 b for holding (supporting) the lip end portion13 b certainly from the reverse (back) side, and deformation in pressurereception (refer to marks P) is prevented. The shaft seal demonstratesexcellent sealability by keeping the inclination angle of the lip endportion 13 b to be 10° to 45°.

[0089] Next, FIG. 4 and FIG. 5 show a modification of the firstpreferred embodiment of the present invention. As clearly shown incomparison with FIG. 1 and FIG. 2, the modification is different infollowing construction.

[0090] That is to say, the first seal element 7 in FIG. 1 is omitted,the seal element E is composed exclusively of the second seal element 8,and the supporting metal 12 has a thickness dimension T enough tocompensate the lack of the first seal element 7. And, the slopereceiving face A is an end face of the supporting metal 12 (from whichthe bent portion 17 in FIG. 1 is omitted) made as to tightly fit to andsupport the reverse face (back face) side of the lip portion 13 of theseal member 5.

[0091] The inclination angleθ of the slope receiving face A with theaxis L of the rotation shaft is set within the range of theabove-described first preferred embodiment. Explanation of other partsindicated with same marks as in the first preferred embodiment isomitted, since they are similarly constructed as in the first preferredembodiment.

[0092] Next, examples will be described.

[0093] A shaft seal having the construction shown in FIG. 1 and FIG. 2B(example 1) and a shaft seal having the construction shown in FIG. 1 andFIG. 2A (example 2) were made and tested for sealability under thefollowing test condition.

[0094] Test condition:

[0095] (1) Sealed Fluid: (refrigerating machine oil+CO₂)

[0096] (2) Sealing Pressure: 2.45 MPa (25 kgf/cm²)

[0097] (3) Rotation Speed: 3.74 m/s

[0098] (4) Temperature: 60° C.

[0099] The result of the above test is shown in following Table 1. TABLE1 RESULT OF THE TEST Time of the Operation Total Amount of Leakage (h)Time (h) Leakage (g) EXAMPLE 1 — 500 0 EXAMPLE 2 415 438 1.36CONVENTIONAL 70.5 120 1.23 EXAMPLE

[0100] The above Table 1 shows that the supporting metal 12 preventsdeformation of the lip end portion 13 b, increase of contact area of theseal with the rotation shaft 32, and, heat and abrasion. And, Table 1also shows that time until the leakage (life time of the seal) isfurther extended by the R-shaped chamfer 20 as in FIG. 2B.

[0101] Next, a second preferred embodiment of the present invention isshown in FIG. 6 through FIG. 12. As clearly shown in comparison with thefirst preferred embodiment shown in FIG. 1 through FIG. 5, the secondpreferred embodiment is different in.following construction. Explanationof parts indicated with same marks as in the first preferred embodimentis omitted, since they are similarly constructed as in the firstpreferred embodiment.

[0102] That is to say, as shown in FIG. 6, a reinforcing cover metal 21is formed unitedly with the inner brim portion 2 of the outer case 1. Todescribe concretely, the supporting metal 12 is disposed between thefirst seal element 7 and the seal member 5 of rubber. A part from theinner peripheral face of the lip end portion 13 b to a back face of theinner brim cover portion (standing portion) 5 b (standing in a directionat right angles with the rotation shaft 32) through the short cylinderportion 13 a, is held by the supporting metal 12 of ring, a part fromthe peripheral face of the lip end portion 13 b to the peripheral faceof the short cylinder portion 13 a is covered with the reinforcing covermetal 21, and the lip end portion 13 b (leaving the tip end portion 14)is sandwiched between the supporting metal 12 and the reinforcing covermetal 21.

[0103] As shown in FIG. 6 and FIG. 7, the lip end portion 13 b has aninclination angle of 10° to 45° to the axis L of the rotation shaft 32,and, corresponding to the inclination angle, the supporting metal 12 hasthe slope receiving face A has an inclination angleθ of 10° to 45° tothe axis L.

[0104] The reinforcing cover metal 21 covering the outer face of the lipend portion 13 b, as described above, is formed unitedly with the innerbrim portion 2 of the outer case made of metal. That is to say, as inFIG. 7A and FIG. 7B, the reinforcing cover metal 21 is unitedly attachedto the outer face of the lip end portion 13 b with adhesion or bakingleaving the tip end portion 14.

[0105] High pressure P is prevented from working directly on the wholelip end portion 13 b by the reinforcing cover metal 21. And, highsealability is secured by cooperation of the reinforcing cover metal 21with the supporting metal 12 to reduce the deformation of the lip endportion 13 b when the pressure in the fluid storing chamber 33 isrelatively high (3 to 10 MPa, for example).

[0106] In further concrete description, the reinforcing cover metal 21does not cover the whole of the lip end portion 13 b, an end of thereinforcing cover metal 21 is extended to a position leaving the tip endportion 14 of the lip end portion 13 b which linearly contacts therotation shaft 32. In other words, an exposed portion 13 c not coveredby the reinforcing cover metal 21 is on the peripheral face of the lipend portion 13 b closer to the tip end side than the position, the highpressure P works directly only on the exposed portion 13 c, andappropriate linear contact state is formed (by cooperation with thesupporting metal 12) between the tip end portion of the lip end portion13 b and the rotation shaft 32 thereby to secure the high sealability.

[0107] The inner peripheral face of a root portion (near a bent portion17) of the lip end portion 13 b having the exposed portion 13 c on theouter face is supported by the slope receiving face A of the supportingmetal 12 as described above, the root portion of the lip end portion 13b sandwiched between the supporting metal 12 and the reinforcing covermetal 21 is sufficiently reinforced on both of inner and outer sidesthereby. Therefore, the whole lip end portion 13 b is not greatlydeformed when the high pressure P works, area contact state of excessivepressure between the lip end portion 13 b and the rotation shaft 32 isprevented, and early abrasion of the lip portion 13 is preventedthereby.

[0108] The supporting metal 12, the first inner case 9, the second innercase 11, the washer 10, the reinforcing cover metal 21, and the outercase 1 are made of metal such as steel, and, the first seal element 7and the second seal element 8 are made of fluororesin such as PTFE,further, the seal member 5 is, considering cooling medium resistance,made of HNBR of which JIS hardness is preferably set to be 87 to 96 (bycomposition of HNBR) to prevent deformation when the seal receivespressure. The seal member is greatly deformed when the JIS hardness islower than 87, and slightly poor in elasticity when the JIS hardness ishigher than 96.

[0109] To make this kind of pressure-resisting rotation shaft seal, asshown in FIG. 6, the supporting metal 12, the first seal element 7, thefirst inner case 9, the washer 10, the second seal element 8, and thesecond inner case 11 are serially fitted to the outer case 1 unifiedwith the seal member 5 of rubber by adhesion, etc. beforehand in astraight state (a cylindrical state) in which (the reinforcing covermetal 21 and) the inner brim portion 3 of the outer case 1 are notformed. And then, the inner brim portion 3 is bent and formed bycaulking and the all parts are unified.

[0110] Especially, the unification with the seal member 5 of rubber ismade stronger by forming an opening hole 19 on the inner brim portion 2of the outer case 1 beforehand. Further, when preliminary formed rubberis formed with the inner brim portion 2, inside of the inner brim coverportion 5 b (standing portion) is easily filled with the preliminaryformed rubber through the opening hole 19.

[0111] Next, FIG. 8 and FIG. 9A show a modification of the secondpreferred embodiment of the present invention. In this case, thereinforcing cover metal 21, covering a part from the peripheral face ofthe lip end portion 13 b to the standing portion (the inner brim coverportion) 5 b through the peripheral face of the short cylinder portion13 a, is formed separately from the outer case 1, and a part of the sealmember 5 is disposed between the reinforcing cover metal 21 and theinner brim portion 2 of the outer case 1. And, in this case, thereinforcing cover metal 21, in which an end portion 21 a covering theperipheral face of the lip end portion 13 b and the short cylinderportion 13 a, and a base portion 21 b covering the standing portion 5 bare uniformly formed, has an approximately L-shaped or J-shaped crosssection.

[0112] In this case too, the exposed portion 13 c not covered with thereinforcing cover metal 21 is formed on the peripheral face of the endof the lip end portion 13 b, and the tip end portion 14 of the lipportion corresponding to the exposed portion 13 c becomes linear contactstate of appropriate pressure with the rotation shaft 32 as the secondpreferred embodiment. And, as shown in FIG. 9B, the R-shaped chamfer 20is preferably formed on an end corner portion of the slope receivingface A of the supporting metal 12 to effectively prevent the end cornerportion of the supporting metal 12 from biting into the lip end portion13 b to cause fissures in the lip end portion 13 b as the firstpreferred embodiment.

[0113] Further, FIG. 10 and FIG. 11 show another modification of thesecond preferred embodiment of the present invention. In this case, thefirst seal element 7 is omitted, the seal element E is composedexclusively of the second seal element 8, and the supporting metal 12has a thickness dimension T enough to compensate the lack of the firstseal element 7. And, the slope receiving face A is an end face of thesupporting metal 12 (from which the bent portion 17, etc. in FIG. 6 areomitted) made as to tightly fit to and support the reverse face (backface) side of the lip portion 13 of the seal member 5.

[0114] In this case, similar working effect to the embodiment shown inFIG. 6 and FIG. 7 is obtained. The inclination angle θ of the slopereceiving face A with the axis L of the rotation shaft is set within therange of the embodiment shown in FIG. 6 and FIG. 7. Explanation of sameparts indicated with same marks is omitted. And, although not shown inFigures, the embodiment shown in FIG. 10 and FIG. 11 may be combinedwith the embodiment shown in FIG. 8 and FIG. 9.

[0115] And, FIG. 12A and FIG. 12B show modifications of the reinforcingcover metal 21. In a modification shown in FIG. 12A, the end portion 21a of the reinforcing cover metal 21 is extended to the tip end portion14 of the lip portion 13. And, in a modification shown in FIG. 12B, atip of the end portion 21 a of the reinforcing cover metal 21 is bent tothe lip portion 13 side (forming a bent portion 21 c), and the bentportion 21 c hitches onto the tip end face 14 a of the tip end portion14 of the lip portion 13. By these compositions, exfoliation of thereinforcing cover metal 21 from the lip portion 13 is prevented. And,the modifications in FIG. 12A and FIG. 12B may be combined with theformer-described preferred embodiments.

[0116] And, the construction members such as the outer case, the sealelement, the supporting metal, the reinforcing cover metal, etc. are notrestricted to the embodiments described above. Each of the aboveconstruction members may be modified in design or improved correspondingto service condition, etc., and the present invention can be applied toany configurations and combinations of the construction members as longas the inner peripheral face of the lip end portion of the sealingmember of rubber is held by the supporting metal, the peripheral face ofthe lip end portion is covered with the reinforcing cover metal, and thelip end portion is reinforced by the supporting metal and thereinforcing cover metal which sandwich the lip end portion.

[0117] Next, FIG. 13 through FIG. 23 show a third preferred embodimentof the rotation shaft seal relating to the present invention. As clearlyshown in comparison with the above-described first and second preferredembodiments, the embodiment is different in following construction.Explanation of the members of the same marks is omitted because themembers are similarly constructed as in the former embodiments.

[0118] As shown in FIG. 13, a gap portion S is formed between the sealmember 5 of rubber and the supporting metal 12 disposed as to supportthe back face of the seal member 5 of rubber. To describe concretely,the supporting metal 12 is disposed between the first seal element 7 andthe seal member 5 as to partially fit to and hold the lip portion 13with the gap portion S on an opposite part to the fluid storing portionof the inner brim cover portion 5 b of the seal member 5, the shortcylinder portion 13 a, and the lip end portion 13 b.

[0119] As shown in FIG. 13 and FIG. 14, the lip end portion 13 b has aninclination angle of 10° to 45° to the axis L of the rotation shaft 32,and, corresponding to the inclination angle, the supporting metal 12 hasthe slope receiving face A has an inclination angle θ of 10° to 45° tothe axis L.

[0120] Concretely, the supporting metal 12, of which cross section isapproximately L-shaped, is composed of a flat board portion 15 at rightangles with the axis L, and a cylinder portion 16 of short cylinder ofwhich center is the axis L. An end portion 16 a (on the fluid storingchamber 33 side) of the cylinder portion 16 is bent with the aboveinclination angleθ at a bent portion 17 as to diminish in diametergradually to the end, and a peripheral face of the end portion 16 aforms the former-mentioned slope receiving face A.

[0121] The bent portion 17 tightly fits to an end side to the shortcylinder portion 13 a and a bent inner corner of the lip end portion 13b. That is to say, the cylinder portion 16 of the supporting portion 12,forming the gap portion S, does not fit to (hold) the short cylinderportion 13 a of the lip portion 13 and a part of the lip end portion 13b, while the end portion 16 a (the slope receiving face A) of thesupporting metal 12 fits to (holds) the lip end portion 13 b.

[0122] And, as shown in FIG. 14B, it is preferable to form an R-shapedchamfer 20 on an end corner portion of the slope receiving face A of thesupporting portion 12. That is to say, in pressurizing (operation) stateof the fluid storing chamber 33 (refer to FIG. 13), an end cornerportion of the supporting metal 12 is effectively prevented from bitinginto the lip end portion 13 b of the lip portion 13 to cause fissures inthe lip end portion 13 b when high pressure of the fluid works.

[0123] And, as shown in FIG. 13, the outer case 1 is unified with theseal member 5 of rubber by adhesion, etc. beforehand. The supportingmetal 12, the first seal element 7, the first inner case 9, the washer10, the second seal element 8, and the second inner case 11 are seriallyfitted to the outer case 1 in a straight state (a cylindrical state) inwhich the inner brim portion 3 is not formed. Then, the inner brimportion 3 is formed by caulking and the all parts are unified.

[0124] The supporting metal 12, the first inner case 9, the second innercase 11, the washer 10, and the outer case 1 are made of metal such assteel. The first seal element 7 and the second seal element 8 are madeof fluororesin such as PTFE. Further, the seal member 5 is, consideringcooling medium resistance, made of HNBR of which JIS hardness ispreferably set to be 87 to 96 (by composition of HNBR) to preventdeformation when the seal receives pressure. The seal member is greatlydeformed when the JIS hardness is lower than 87, and slightly poor inelasticity when the JIS hardness is higher than 96.

[0125] And, the seal member 5 of rubber, corresponding to pressureincrease of the fluid storing chamber 33, elastically deforms mainly ina diminishing direction of the short cylinder portion 13 a as to getinto the gap portion S. In the third embodiment of the presentinvention, the lip end portion 13 b is drawn in a parting direction fromthe rotation shaft 32 by utilizing the elastic deformation.

[0126] To describe concretely, firstly, as shown in FIG. 16A, in theseal member 5 of rubber in non-attached state (free state) to therotation shaft 32, the gap portion S is disposed between the seal member5 of rubber (the lip portion 13) and the supporting metal 12, and theback face of the lip end portion 13 b is held by the slope receivingface A of the supporting metal 12.

[0127] And, as shown in FIG. 16B, the short cylinder portion 13 a of thelip portion 13 elastically deforms as to get into the gap portion S whenpressure P (of high-pressure fluid, etc.) works on the seal member 5 ofrubber (the lip portion 13). That is to say, locomotion force F_(x) forelastic deformation in the axis L direction of the rotation shaft 32(refer to FIG. 13) and pressing force F_(y) for elastic deformation invertical direction to the axis L work on the lip portion 13.

[0128] In this case, the lip end portion 13 b of the lip portion 13 isdrawn in the parting direction from the rotation shaft 32 along theslope receiving face A by the locomotion force F_(x). That is to say,tensile force F₁ works on an end corner portion 27 of the lip endportion 13 b in the parting direction from the rotation shaft 32.

[0129] And, when the seal member 5 of rubber is attached to the rotationshaft 32 and the fluid storing chamber 33 is not pressurized, as shownin FIG. 17A, the lip portion 13 parts from the slope receiving face A,the gap portion S is enlarged, and the elastically-pushed seal member 5of rubber (the lip portion 13) linearly contact (the peripheral face of)the rotation shaft 32. That is to say, tightening force F₃ generated byelasticity of rubber works on a contact portion 22 (an end cornerportion 27) of the lip end portion 13 b (with the rotation shaft 32)toward the rotation shaft 32.

[0130] And, as shown in FIG. 17B, in pressurized (operation) state ofthe fluid storing chamber 33, self-sealing force F₄ (generated by thepressurization), (the above-mentioned) tightening force F₃, and (theabove-mentioned) tensile force F₁ work on the contact portion 22 (theend corner portion 27) of the lip end portion 13 b toward the rotationshaft 32. That is to say, total force F₅ (=F₃+F₄−F₁) works on thecontact portion 22 (the end corner portion 27) of the lip end portion 13b toward the rotation shaft 32.

[0131] Therefore, in comparison with the case (in which the gap portionS does not exist in the non-attached state to the rotation shaft 32)shown in the conventional example (FIG. 41), force working on therotation shaft 32 decreases (for the tensile force F₁), contact pressureof the contact portion 22 of the lip end portion 13 b is reduced, andabrasion is reduced thereby.

[0132] Further, an R portion 18 is formed on the root of the lip portion13 on the liquid storing chamber 33 side to lessen the elasticdeformation of the root of the lip portion 13 by increasing pressure inthe liquid storing chamber 33. That is to say, in comparison with theconventional example (FIG. 42), the lip portion has an R-shapedconfiguration instead of the concave portion (44), smallerpressure-receiving area on the fluid storing chamber 33 side, and amountof rubber of the root of the lip portion 13 is increased.

[0133] Therefore, in operation state in which the pressure in the fluidstoring chamber 33 is increased, stress (of the pressure) is dispersed,and the elastic deformation of the root of the lip portion 13 isreduced. Fissures on the root of the lip portion 13 and exfoliation ofthe seal member 5 of rubber (the inner brim cover portion 5 b) from theouter case 1 (the inner brim portion 2) are hardly generated, andcontact pressure of (the contact portion 22 of) the lip end portion 13 bis decreased further to reduce abrasion.

[0134] And, when the pressure P works on the lip end portion 13 b, thelip end portion 13 b is received (supported) by the slope receiving faceA of the supporting metal 12 from the reverse side (an inner side) toprevent deformation, and sealability of the lip end portion 13 b underhigh pressure can be kept good thereby.

[0135] As described above, in FIG. 14, the slope receiving face A ofwhich inclination angleθ of 10°≦θ≦45° to the axis L is formed on thesupporting metal 12 to approximately correspond to the inclination angleof the lip end portion 13 b for holding (supporting) the lip end portion13 b certainly from the reverse (back) side, and deformation in pressurereception (refer to marks P) is prevented. The shaft seal demonstratesexcellent sealability by keeping the inclination angle of the lip endportion 13 b to be 10° to 45°.

[0136] As the modification of the third preferred embodiment shown inFIG. 15, the backup ring 45 disclosed by Japanese Utility ModelPublication No. 2-47311 proposed in conventional oil seals may beapplied to holding of the lip portion 13 of the seal member 5 of rubber.That is to say, the end 45 a of the backup ring 45 is bent for a rightangle of 90°, and having an extremely short dimension.

[0137] Next, FIG. 18 and FIG. 19 show another modification of the thirdpreferred embodiment of the present invention. As clearly shown incomparison with FIG. 13 and FIG. 14, the modification is different infollowing construction.

[0138] That is to say, the first seal element 7 in FIG. 13 is omitted,the seal element E is composed exclusively of the second seal element 8,and the supporting metal 12 has a thickness dimension T enough tocompensate the lack of the first seal element 7. And, the slopereceiving face A is an end face of the supporting metal 12 (from whichthe bent portion 17 in FIG. 13 is omitted) made as to tightly fit to andsupport the reverse face (back face) side of the lip portion 13 of theseal member 5.

[0139] The inclination angleθ of the slope receiving face A with theaxis L of the rotation shaft is set within the range of theabove-described first preferred embodiment. Explanation of other partsindicated with same marks as in the third preferred embodiment isomitted, since they are similarly constructed as in the third preferredembodiment.

[0140] Next, FIG. 20 shows other modifications of the third preferredembodiment of the present invention. As clearly shown in comparison withFIG. 13, the modification shown in FIG. 20A is different in followingconstruction.

[0141] That is to say, the end face 2 a of the inner brim portion 2 ofthe outer case 1 is positioned on a peripheral side (an outer side indiameter of the rotation shaft 32) to the peripheral face 23 of theshort cylinder portion 13 a of the lip portion 13, and the seal member 5of rubber (the lip portion 13 and the inner brim cover portion 5 b) isformed as to easily deforms in the axis L direction of the rotationshaft 32 (refer to FIG. 13) thereby. Therefore, the seal member 5 ofrubber elastically deforms in the axis L direction of the rotation shaft32 along the pressure increase of the fluid storing chamber 33, and thelip end portion 13 b is drawn in the parting direction from the rotationshaft 32.

[0142] And, the modification shown in FIG. 20B, as clearly shown incomparison with FIG. 13, is different in following construction. That isto say, in unpressurized state of the fluid storing chamber 33, the gapportion S is disposed between the inner brim cover portion 5 b of theseal member 5 of rubber and the flat board portion 15 of the supportingmetal 12, and the seal member 5 of rubber (the lip portion 13 and theinner brim cover portion 5 b) is formed as to easily deforms in the axisL direction of the rotation shaft 32 (refer to FIG. 13) thereby.Therefore, the gap portion S is disposed between the seal member 5 ofrubber and the supporting metal 12 for holding the back face of the sealmember 5 of rubber, and the seal member 5 of rubber elastically deformsaccompanied with the pressure increase of the fluid storing chamber 33to get into the gap portion S, and the lip end portion 13 b is drawn inthe parting direction from the rotation shaft 32. And, plural protrudingportions 24 may be disposed between the inner brim cover portion 5 b andthe flat board portion 15 to form the gap portion between the inner brimcover portion 5 b and the flat board portion 15.

[0143] Further, the modification shown in FIG. 20C, as clearly shown incomparison with FIG. 13, is different in following construction. That isto say, in unpressurized state of the fluid storing chamber 33, aconnecting portion 26 of the flat board portion 15 (of the supportingmetal 12) and the cylinder portion 16 facing a connecting portion 25 ofthe inner brim cover portion 5 b (of the seal member 5) and the lipportion 13 (the short cylinder portion 13 a) is bent opposite to thefluid storing chamber 33 side to make the gap portion S between theconnecting portion 25 (of the seal member 5) and the connecting portion26 (of the supporting metal 12), and the seal member 5 of rubber (thelip portion 13) is formed as to easily deforms in the axis L directionof the rotation shaft 32 (refer to FIG. 13) thereby. Therefore, the gapportion S is disposed between the seal member 5 of rubber and thesupporting metal 12 for holding the back face of the seal member 5 ofrubber, and the seal member 5 of rubber elastically deforms accompaniedwith the pressure increase of the fluid storing chamber 33 to get intothe gap portion S to give force to the lip end portion 13 b in theparting direction from the rotation shaft 32.

[0144] And, the modification shown in FIG. 20D, as clearly shown incomparison with FIG. 13, is different in following construction. That isto say, in unpressurized state of the fluid storing chamber 33, theshort cylinder portion 13 a (the connecting portion 25 of the inner brimcover portion 5 b and the lip portion 13) is parted from the cylinderportion 16 as the short cylinder portion 13 a of the seal member 5 ofrubber and the cylinder portion 16 of the supporting metal 12 do notcontact each other, and the seal member 5 of rubber (the lip portion 13)is formed as to easily deforms in the axis L direction of the rotationshaft 32 (refer to FIG. 13) thereby. Therefore, the gap portion S isdisposed between the seal member 5 of rubber and the supporting metal 12for holding the back face of the seal member 5 of rubber, and the sealmember 5 of rubber elastically deforms accompanied with the pressureincrease of the fluid storing chamber 33 to get into the gap portion Sas force, which draws the lip end portion 13 b in the parting directionfrom the rotation shaft 32, works.

[0145] And, in an unpressurized state of the fluid storing chamber 33(as shown in FIG. 20A through FIG. 20C), if the short cylinder portion13 a of the seal member 5 contacts the cylinder portion 16 of thesupporting metal 12, the cylinder portion 16 or a contact portion (theconnecting portion 25 of the inner brim cover portion 5 b and the lipportion 13) may be treated with low friction resin coating to reduce thefrictional force, and the seal member 5 of rubber (the lip portion 13and the inner brim cover portion 5 b) is formed as to easily deforms inthe axis L direction of the rotation shaft 32 (refer to FIG. 13)thereby.

[0146] And, these (individual) constructions shown in FIG. 20A throughFIG. 20D may be combined in various methods, and the seal member 5 ofrubber (the lip portion 13 and the inner brim cover portion 5 b) may beformed as to easily deform, accompanied with the pressure increase ofthe fluid storing chamber 33, in the axis L direction of the rotationshaft 32 (refer to FIG. 13) thereby.

[0147] Next, FIG. 21 and FIG. 22 show still another modification of thethird preferred embodiment of the present invention. As clearly shown incomparison with FIG. 16 and FIG. 17, the modification is different infollowing construction.

[0148] That is to say, the gap portion S in FIG. 16A between the lipportion 13 and the supporting metal 12 (the cylinder portion 16) doesnot exist, and another gap portion S is formed between the supportingmetal 12 and the connecting portion 25 of the inner brim cover portion 5b (of the seal member 5) and the lip portion 13 (the short cylinderportion 13 a).

[0149] To describe concretely, as shown in FIG. 21A, in the seal member5 of rubber in non-attached state (free state) to the rotation shaft 32,the gap portion S is disposed between, the connecting portion 25 of theinner brim cover portion 5 b and the lip portion 13, and, the connectingportion 26 of the flat board portion 15 and the cylinder portion 16 (ofthe supporting metal 12), and the short cylinder portion 13 a and thelip end portion 13 b of the lip portion 13 are supported by the cylinderportion 16 and the slope receiving face A of the supporting metal 12 fitto the lip portion 13.

[0150] And, as shown in FIG. 21B, the lip portion 13 elastically deformsas to get into the gap portion S (as the connecting portion 25 contactsthe connecting portion 26) when pressure P (of high-pressure fluid,etc.) works on the seal member 5 of rubber (the lip portion 13). That isto say, locomotion force F_(x) for elastic deformation in the axis Ldirection of the rotation shaft 32 (refer to FIG. 13) and pressing forceF_(y) for elastic deformation in vertical direction to the axis L workon the lip portion 13.

[0151] In this case, the lip end portion 13 b of the lip portion 13 isdrawn in the parting direction from the rotation shaft 32 along theslope receiving face A by the locomotion force F_(x). That is to say,tensile force F₁ works on an end corner portion 27 of the lip endportion 13 b in the parting direction from the rotation shaft 32.

[0152] And, when the seal member 5 of rubber is attached to the rotationshaft 32 and the fluid storing chamber 33 is not pressurized, as shownin FIG. 22A, the lip portion 13 parts from the slope receiving face A,the gap portion S is enlarged, and the elastically-pushed seal member 5of rubber (the lip portion 13) linearly contact (the peripheral face of)the rotation shaft 32. That is to say, tightening force F₃ generated byelasticity of rubber works on a contact portion 22 (an end cornerportion 27) of the lip end portion 13 b (with the rotation shaft 32)toward the rotation shaft 32.

[0153] And, as shown in FIG. 22B, in pressurized (operation) state ofthe fluid storing chamber 33, self-sealing force F₄ (generated by thepressurization), (the above-mentioned) tightening force F₃, and (theabove-mentioned) tensile force F₁ work on the contact portion 22 (theend corner portion 27) of the lip end portion 13 b toward the rotationshaft 32. That is to say, total force F₅ (=F₃+F₄−F₁) works on thecontact portion 22 (the end corner portion 27) of the lip end portion 13b toward the rotation shaft 32.

[0154] Therefore, in comparison with the case (in which the gap portionS does not exist in the non-attached state to the rotation shaft 32)shown in the conventional example (FIG. 41), force working on therotation shaft 32 diminishes (for the tensile force F₁), abrasion (ofthe contact portion 22) of the lip end portion 13 b is reduced. And, incomparison with the case shown in FIG. 16 and FIG. 17, the seal ishighly stable in the non-attached state to the rotation shaft 32 becausethe short cylinder portion 13 a of the seal member 5 of rubber is fit toand supported by the cylinder portion 16 of the supporting metal 12.

[0155] Next, FIG. 23 shows further modifications of the third preferredembodiment of the present invention. That is to say, the short cylinderportion 13 a and the lip end portion 13 b of the lip portion 13 are fitto and supported by the slope receiving face A and the cylinder portion16 of the supporting metal 12, and the individual constructions shown inFIG. 20B through FIG. 20D are combined.

[0156] To describe concretely, as shown in FIG. 23A, in theunpressurized state of the fluid storing chamber 33, the gap portion Sis disposed between the inner brim cover portion 5 b of the seal member5 of rubber and the flat board portion 15 of the supporting metal 12,and the seal member 5 of rubber (the lip portion 13 and the inner brimcover portion 5 b) is formed as to easily deforms in the axis Ldirection of the rotation shaft 32 (refer to FIG. 13) thereby.Therefore, the seal member 5 of rubber elastically deforms accompaniedwith the pressure increase of the fluid storing chamber 33 in theparting direction from the rotation shaft 32, and the lip end portion 13b is drawn in the parting direction from the rotation shaft 32. And,plural protruding portions 24 may be disposed between the inner brimcover portion 5 b and the flat board portion 15 to form the gap portionS between the inner brim cover portion 5 b and the flat board portion15.

[0157] And, as shown in FIG. 23B, in the unpressurized state of thefluid storing chamber 33, a connecting portion 26 of the flat boardportion 15 (of the supporting metal 12) and the cylinder portion 16facing a connecting portion 25 of the inner brim cover portion 5 b (ofthe seal member 5) and the lip portion 13 (the short cylinder portion 13a) is bent opposite to the fluid storing chamber 33 side to make the gapportion S between the connecting portion 25 (of the seal member 5) andthe connecting portion 26 (of the supporting metal 12), and the sealmember 5 of rubber (the lip portion 13) is formed as to easily deformsin the axis L direction of the rotation shaft 32 (refer to FIG. 13)thereby.

[0158] And, in an unpressurized state of the fluid storing chamber 33(as shown in FIG. 23A and FIG. 23B), a contact face of the shortcylinder portion 13 of the seal member 5 and the cylinder portion 16 ofthe supporting metal 12 may be treated with low friction resin coatingto reduce the frictional force, and the seal member 5 of rubber (the lipportion 13 and the inner brim cover portion 5 b) is formed as to easilydeforms in the axis L direction of the rotation shaft 32 (refer to FIG.13) thereby.

[0159] And naturally, these (individual) constructions shown in FIG. 23Aand FIG. 23B may be combined in various methods, and the seal member 5of rubber (the lip portion 13 and the inner brim cover portion 5 b) maybe formed as to easily deform, accompanied with the pressure increase ofthe fluid storing chamber 33, in the axis L direction of the rotationshaft 32 (refer to FIG. 13) thereby.

[0160] And, although not shown in Figures, the seal member may be formedas to have the end corner portion 27 which linearly contacts or slightlypart from the rotation shaft 32 without interference in theunpressurized state, and contacts the rotation shaft 32 in thepressurized state. And, the tightening force F₃ (refer to FIG. 17) doesnot work on the contact portion 22 of the lip end portion 13 b (the endcorner portion 27) when the seal is attached to the rotation shaft 32.Therefore, abrasion is reduced further in comparison with theconventional example (in FIG. 41) because contact pressure of the lipend portion 13 b onto the surface of the rotation shaft 32 is decreasedby synergistic effect of that interference does not exist, and the sealhas the gap portion S.

[0161] Next, FIG. 24 through FIG. 30 show a fourth preferred embodimentof the present invention. As clearly shown in comparison with the firstthrough third preferred embodiments described above, the fourthpreferred embodiment is different in following construction. Explanationof parts indicated with same marks as in the former preferredembodiments is omitted, since they are similarly constructed as in theformer preferred embodiments.

[0162] That is to say, as shown in FIG. 24, configuration and dimensionsof the end corner portion 27 of the lip end portion 13 b are set as theend corner portion 27 linearly contacts without interference or slightlyparts from (the peripheral face of) the rotation shaft 32 inunpressurized state. The interference is equivalent to the mark G of theconventional example in FIG. 42, “without interference” means G≈0 , and“slightly part from” means G<0.

[0163] And, the supporting metal 12 is disposed between the first sealelement 7 and the seal member 5 as to fit to and support an oppositeside to the fluid storing chamber or inner portion of the inner brimcover portion 5 b of the seal member 5, the short cylinder portion 13 a,and the lip end portion 13 b.

[0164] As shown in FIG. 24 and FIG. 25, the lip end portion 13 b has aninclination angle of 10° to 45° to an axis L of the rotation shaft 32,and the supporting metal 12, as to correspond to the lip end portion 13b, has a slope receiving face A on its end as to have an inclinationangleθ of 10° to 45° to the axis L.

[0165] Concretely, the supporting metal 12, of which cross section isapproximately L-shaped, is composed of a flat board portion 15 at rightangles with the axis L, and a cylinder portion 16 of short cylinder ofwhich center is the axis L. An end portion 16 a (on the fluid storingchamber 33 side) of the cylinder portion 16 is bent with the aboveinclination angleθ at a bent portion 17 as to diminish in diametergradually to the end, and a peripheral face of the end portion 16 aforms the former-mentioned slope receiving face A.

[0166] The bent portion 17 corresponds and tightly fits to the shortcylinder portion 13 a of the seal member 5 and a bent inner corner ofthe lip end portion 13 b. And, as shown in FIG. 25B, it is preferable toform an R-shaped chamfer 20 on an end corner portion of the slopereceiving face A of the supporting metal 12. That is to say, an endcorner portion of the supporting metal 12 is effectively prevented frombiting into the lip end portion 13 b of the lip portion 13 to causefissures in the lip end portion 13 b.

[0167] And, as shown in FIG. 24, the outer case 1 is unified with theseal member 5 of rubber by adhesion, etc. beforehand. The supportingmetal 12, the first seal element 7, the first inner case 9, the washer10, the second seal element 8, and the second inner case 11 are seriallyfitted to the outer case 1 in a straight state (a cylindrical state) inwhich the inner brim portion 3 is not formed. Then, the inner brimportion 3 is formed by caulking and the all parts are unified.

[0168] The supporting metal 12, the first inner case 9, the second innercase 11, the washer 10, and the outer case 1 are made of metal such assteel. The first seal element 7 and the second seal element 8 are madeof fluororesin such as PTFE. Further, the seal member 5 is, consideringcooling medium resistance, made of HNBR of which JIS hardness ispreferably set to be 87 to 96 (by composition of HNBR) to preventdeformation when the seal receives pressure. The seal member is greatlydeformed when the JIS hardness is lower than 87, and slightly poor inelasticity when the JIS hardness is higher than 96.

[0169] And, to describe sealing function, as shown in FIG. 27A, inattached state before the fluid storing chamber is pressurized, the endcorner portion 27 which linearly contacts or slightly part from theperipheral face of the rotation shaft 32 without interference. And asshown in FIG. 27B, self-sealing force F₄ works on the end corner portion27 to the peripheral face of the rotation shaft 32 by pressure P workingon the lip portion 13 in the pressurized state of the fluid storingchamber 33, and the end corner portion 27 linearly contacts the rotationshaft 32 thereby. And, the tightening force (F₁₁) is not generated (ormicro, if generated) onto the peripheral face of the rotation shaft 32because the interference portion (46) of the conventional example (inFIG. 42) does not exist, and the force working on the position of (theend corner portion 27 of) the lip end portion 13 b on the rotation shaft32 is smaller than that of the conventional example (in FIG. 42) for thetightening force (F₁₁).

[0170] Therefore, the force working on the rotation shaft 32 becomessmall, and consequently, abrasion of the lip end portion 13 b is reduced(by decreasing the contact pressure). And, especially in case thathigh-pressure cooling media (such as CO₂) are used, it is effective forsealing when the rotation shaft 32 is stationary because the seal iscontinuously pressurized and negative pressure is not generated.

[0171] And, the lip end portion 13 b is received (supported) by theslope receiving face A of the supporting metal 12 from a reverse side(inner side) and prevented from being deformed when pressure P works onthe lip end portion 13 b on the fluid storing chamber 33 side (as shownin FIG. 2), and good sealability of the lip end portion 13 b is keptgood under high pressure.

[0172] As described above, the slope receiving face A of whichinclination angleθ of 10°≦θ≦45° to the axis L is formed on thesupporting metal 12 to approximately correspond to the inclination angleof the lip end portion 13 b for holding (supporting) the lip end portion13 b certainly from the reverse (back) side, and deformation in pressurereception (refer to marks P) is prevented. The shaft seal demonstratesexcellent sealability by keeping the inclination angle of the lip endportion 13 b to be 10° to 45°.

[0173]FIG. 26 shows a modification of the fourth preferred embodiment,in which the backup ring 45, proposed in conventional oil seals anddisclosed by Japanese Utility Model Publication No. 2-47311, is appliedto holding of the lip portion 13 of the seal member 5 of rubber. That isto say, the end 45 a of the backup ring 45 is bent for 90°. And theinterference of the end corner portion 27 is set to be 0 (or minus,namely, slightly parted).

[0174] And, as shown in FIG. 24 and FIG. 27A, a distances, between theend corner portion 27 of the lip end portion 13 b and the rotation shaft32 in unpressurized state, is preferably arranged less than 7% of anouter diameter dimension D of the rotation shaft 32 to prevent theabrasion of the end corner portion 27 of the lip end portion 13 b, anddemonstrate excellent sealability. If the distance δ is over 7% of thedimension D, the lip end portion 13 b does not sufficiently contact therotation shaft 32 when the lip portion 13 receives the pressure P (referto FIG. 27B), the fluid leaks, and certain sealing can not be expected.

[0175] Next, FIG. 28 and FIG. 29 show another modification of the fourthpreferred embodiment of the present invention. As clearly shown incomparison with FIG. 24 and FIG. 25, the modification is different infollowing construction.

[0176] That is to say, the first seal element 7 in FIG. 24 is omitted,the seal element E is composed exclusively of the second seal element 8,and the supporting metal 12 has a thickness dimension T enough tocompensate the lack of the first seal element 7. And, the slopereceiving face A is an end face of the supporting metal 12 (from whichthe bent portion 17 in FIG. 24 is omitted) made as to tightly fit to andsupport the reverse face (back face) side of the lip portion 13 of theseal member 5.

[0177] The inclination angleθ of the slope receiving face A with theaxis L of the rotation shaft is set within the range of theabove-described fourth preferred embodiment. Explanation of other partsindicated with same marks as in the fourth preferred embodiment isomitted, since they are similarly constructed as in the fourth preferredembodiment.

[0178] And, FIG. 30 shows a still another modification of the fourthpreferred embodiment of the present invention. As clearly shown incomparison with FIG. 27 and FIG. 29, the modification is different infollowing construction.

[0179] That is to say, as shown in FIG. 30A, in unpressurized state theseal is attached to the rotation shaft 32, the supporting metal 12 has aslope receiving face A which fits to and support the reverse face (backface) side of (the lip end portion 13 b of) the lip portion 13, and agap portion P between the reverse face (back face) side of (the shortcylinder portion 13 a of) the lip portion 13 and the cylinder portion 16of the supporting metal 12.

[0180] And, as shown in FIG. 30B, in pressurized operation, (the shortcylinder portion 13 a of) the lip portion 13 is elastically deformed asto get into the gap portion S by the pressure P working on the fluidstoring chamber 33 side.

[0181] In this case, the lip end portion 13 b of the lip portion 13 isdrawn along the slope receiving face A in a parting direction from therotation shaft 32. That is to say, tensile force F₁ works on the endcorner portion 27 of the lip end portion 13 b in the parting directionfrom the rotation shaft 32.

[0182] As described above, the tensile force F₁ works on the end cornerportion 27 of the lip end portion 13 b in the parting direction from therotation shaft 32. And, (as formerly described) the self-sealing forceF₄ works on the end corner portion 27. Consequently, total force F₅(=F₄−F₁) works on the peripheral face of the rotation shaft 32.

[0183] Therefore, in comparison with the case (the gap portion S doesnot exist) shown in FIG. 27, the force working on the rotation shaft 32becomes small (for the tensile force F₁), and the abrasion of the lipend portion 13 b is reduced further. Further, the abrasion is reducedfurther in comparison with the conventional example (in FIG. 42) becausethe force working onto the surface of the rotation shaft 32 is decreasedby synergistic effect of that the interference portion (46) (theinterference G) in the conventional example (in FIG. 42) does not exist,and the seal has the gap portion S (for the tightening force F₁₁ and thetensile force F₁).

[0184] Next, FIG. 31 through FIG. 40 show a fifth preferred embodimentof the present invention. As clearly shown in comparison with the firstthrough the fourth preferred embodiments, the fifth preferred embodimentis different in following construction. Explanation of the partsindicated with same marks as in the former preferred embodiments isomitted, since they are similarly constructed as in the former preferredembodiments.

[0185] That is to say, as shown in FIG. 31, a gas shielding member 51,which shields cooling medium gas (CO₂) permeating seal portions 53comprising the seal element E and the seal member 5 of rubber, isattached instead of the supporting metal 12. And, in FIG. 31, the sealelement E is composed of only one seal element 7.

[0186] To describe concretely, a circular metal thin plate 54 as the gasshielding member 51 is disposed between neighboring two seal portions 53(the (first) seal element 7 and the seal member 5 of rubber) except asliding portion 52 which slides on the rotation shaft 32. The metal thinplate 54 tightly fit to the inner peripheral face of the seal member 5almost entirely except only the sliding portion 52 of the lip endportion 13 b. That is to say, the metal thin plate 54 is preliminaryformed as to tightly fit to the inner peripheral face of the lip portion13 in a free state before the seal is attached shown in FIG. 32, and anend portion of the metal thin plate 54 pushes the lip portion 13 to theperiphery side with slight force as the lip portion 13 is raised alittle. Therefore, the metal thin plate 54 is kept tightly fitting tothe inner peripheral face of the lip portion 13 in the state in whichthe seal is attached to the rotation shaft 32. The metal thin plate 54is held between the both seal portions 53 by force of the both sealportions 53 (the (first) seal element 7 and the seal member 5 of rubber)pushing each other. And, the metal thin plate 54 is also for supportingthe seal portion 53 (the seal member 5 of rubber). And, the metal thinplate 54 may be attached to the seal portion 53 (the seal member 5 ofrubber) with adhesive.

[0187] Carbon dioxide, used as the cooling medium in the compressor, hasconsiderably high permeability against rubber and resin, material forthe seal portion 53. For this, the metal thin plate 54 blocks up apassage of the cooling medium gas permeable to rubber and resin(including passages of gas permeation through the seal portions 53)almost entirely as to shield between an inner side and an atmosphere(outer) side of a housing 31. That is to say, the cooling medium gas inthe housing 31 is mostly shielded by the metal thin plate 54 to enhancesealing characteristics of the seal. The metal thin plate 54 is flexibleas not to spoil the elasticity of the seal portion 53 (the seal member 5of rubber), and able to deform along the seal portion 53 (the sealmember 5 of rubber) keeping the fitting.

[0188] The metal thin plate 54 is different from the supporting metal 12made of metal in fitting and holding ability to the seal portion 53 (theseal member 5 of rubber) which is caused by difference of thickness. Inthe attached state of the seal, the metal thin plate 54 can deformelastically along the seal portion 53 (the seal member 5 of rubber)keeping the fitting because the plate 54 is thin, while the relativelythick and rigid supporting metal 12, unable to deform elastically alongthe seal portion 53 keeping the fitting to the seal portion 53, partsfrom the seal portion 53.

[0189] The thickness of the metal thin plate 54 is, for example, around0.1 mm to 0.5 mm. For this thinness, the metal thin plate 54 can pushand fit to the seal member 5 of rubber with a very slight force, deformelastically along the elastic deformation of the seal member 5 of rubberwhich contacts the peripheral face of the rotation shaft 32, and thefitting state of the metal thin plate 54 and the seal member 5. Thethickness of the metal thin plate 54 may be set to be other valueswithin a range in which the above characteristics (the fitting andholding ability) is obtained. Although the values are influenced bymetals used for the metal thin plate 54, a certain effect is expectedwith a thickness less than 0.6 mm. Especially, a considerable effect isexpected with a thickness less than 0.4 mm, and a remarkable effect isexpected with a thickness less than 0.2 mm. The thickness is by no meansrestricted to these values.

[0190] The material of the metal thin plate 54 is, for example, iron inthe present embodiment, while stainless steel and aluminum may be used.As other metals, general metals used industrially and generally such ascopper, nickel, zinc, lead, tin, etc. may be widely used.

[0191] The rotation shaft seal of the present embodiment provided withthe metal thin plate 54 was compared with another comparison shaft sealnot provided with the metal thin plate 54 in gas-leakage restrictingeffect, and the result shown in a graph of FIG. 33 was obtained. Carbondioxide was used as the cooling medium, and amount of leakage of thecooling medium gas from a position between the rotation shaft 32 and thehousing 31 was measured on the compressor of each of the seal. As shownin the graph of FIG. 33, amount of gas leakage of the seal of thepresent embodiment is reduced to {fraction (1/20)} of that of thecomparison shaft seal.

[0192] Therefore, according to the present embodiment, following effectsare obtained.

[0193] (1) Leakage of the cooling medium gas is regulated to be verysmall when the cooling medium is carbon dioxide having high permeationagainst rubber and resin, namely material of the seal portions 53,because the metal thin plate 54 tightly fits to the surface of the sealportion 53 (the seal member 5 of rubber) as to shield the passage of thegas (attachment area of the seal) almost entirely. Therefore, earlyshortage of the cooling medium in the compressor and reduction ofcooling effect by the shortage of the cooling medium are prevented.

[0194] (2) The passage of the gas is more widely blocked to enhance thesealability because the metal thin plate 54 fits to the seal portion 53(the seal member 5 of rubber) covering a large area to the end portionof the lip portion 13 except the sliding portion 52. And, if the sealportion 53 (the seal member 5 of rubber) parts from the metal thin plate54 on its middle portion, leakage of carbon dioxide is not generatedbecause the metal thin plate 54 fits to the seal portion 53 (the sealmember 5 of rubber) even near the end portion.

[0195] (3) Gaps between the metal thin plate 54 and the seal portion 53(the seal member 5 of rubber) are limited to generate and the passage ofgas leakage is blocked by the metal thin plate 54 sandwiched between thetwo seal portions 53 (the (first) seal element 7 and the seal member 5of rubber), and high sealing ability is obtained.

[0196] (4) The metal thin plate 54, working also as the supporting metal12, contributes to improvement of the sealability of the seal portion 53(the seal member 5 of rubber).

[0197] (5) In case that the metal thin plate 54 is attached to thesurface of the seal portion 53 (the seal member 5 of rubber) withadhesive, gaps are not generated between the metal thin plate 54 and theseal portion 53 (the seal member 5 of rubber), and the sealing abilityis enhanced thereby.

[0198] Next, FIG. 34 shows a first modification of the fifth preferredembodiment. Same parts in the fifth preferred embodiment are indicatedwith same marks, and explanation of them is omitted.

[0199] That is to say, the metal thin plate 54, shorter than the metalthin plate 54 of the above embodiment (shown in FIG. 31), exists only ona border area of the two seal portions 53 (the (first) seal element 7and the seal member 5 of rubber). This is to prevent the rigidity of themetal thin plate 54 from spoiling the elasticity of the lip portion 13.The lip portion 13 can deform elastically into an appropriateconfiguration for sealing when the lip portion 13 contacts theperipheral face of the rotation shaft 32, and the sliding portion 52 ispressed to contact the peripheral face of the rotation shaft 32 firmly.

[0200] Therefore, according to the first modification, following effectis obtained.

[0201] (6) In comparison with the above embodiment, sealing ability atthe sliding portion 52 of the lip end portion 13 b is enhanced althoughgas leakage by permeation is slightly inferior to that of the aboveembodiment.

[0202] Next, FIG. 35 shows a second modification and FIG. 36 shows athird modification. These are seals of different types from that of theformer embodiments.

[0203] That is to say, as shown in the second modification in FIG. 35,this seal is provided with a seal member 55 of rubber as the sealportion 53. The configuration of the seal member 55 of rubber is keptcircular by a holding metal 56 embedded in the seal member 55. The sealmember 55 of rubber has a sealing lip portion 57 which extends to aninner peripheral side. The sealing lip portion 57 is pushed to therotation shaft 32 by pushing force of a ring spring 58 attached to aback face (outer peripheral face) of the sealing lip portion 57, and asliding portion 59 of the sealing lip portion 57 is pressed to thepheral face of the rotation shaft 32.

[0204] And, as shown in the third modification in FIG. 36, this seal isprovided with a seal member 55 of rubber as the seal portion 53. Theconfiguration of the seal member 55 of rubber is kept circular by aholding metal 56 embedded in the seal member 55. The seal member 55 ofrubber has a sealing lip portion 57 which extends to an inner peripheralside. The sealing lip portion 57 is not provided with the ring spring 58in FIG. 35, the sliding portion 59 is pressed to the rotation shaft 32by elastic force of rubber.

[0205] In both types of FIG. 35 and FIG. 36, the sealing lip portion 57is covered entirely with metal film 60 as the gas shielding member 51except the sliding portion 59. The metal film 60, for the same purposein the former embodiments, namely blocking the passage of the coolingmedium gas (including permeation passage in the rubber), covers thepassage of the gas almost entirely.

[0206] In the present embodiment, the metal film 60 is a metalevaporation film. The metal film 60 is not restricted to the metalevaporation film, and may be formed with other film forming methods, forexample, plating (electroless plating). And, material for the metal film60 is, for example, gold with which a gold evaporation film is made.Other metals, with which a fine metal film can be formed, such as iron,stainless steel, aluminum, nickel, tin, silver, copper, etc., may beused. The thickness of the metal film 60, with which the permeation ofthe gas is stopped, for example, around 10 to 100 μm.

[0207] Therefore, according to the second and third modifications,following effect is obtained.

[0208] (7) Wide area of the passage of the gas including near thesliding portion 59 is blocked because the surface of the seal member 55of rubber is covered with the metal film 60. And, elasticity of thesealing lip portion 57 is hardly spoiled for the metal film 60 of whichthickness is thinner than that of the metal thin plate 54 in the formerembodiments. And, flexibility (ability to deform elastically) of thesealing lip portion 57 is secured, and the sealability at the slidingportion 59 is enhanced thereby.

[0209] The fifth preferred embodiment of the present invention, notrestricted to the above description, may be practiced with followingfeatures. That is to say, position of the metal thin plate 54 is notrestricted to between the two seal portions 53. For example, as shown inFIG. 37, the metal thin plate 54 may be fitted to the peripheral faceside of the seal member 5 of rubber. And, as shown in FIG. 38, the metalthin plate 54 may be fitted to the inner peripheral face of the (first)seal element 7 (of resin). Also with these compositions, leakage ofcooling medium gas having high permeability against rubber and resinsuch as carbon dioxide is limited to be small because the cooling mediumgas in the housing 31 is shielded by the metal thin plate 54 fit to thesurface of the seal portion 53 and elastically deforms along the sealportion 53. And, the seal portion 53 is kept by the metal thin plate 54(a backup ring) supporting the seal portion 53 in FIG. 38.

[0210] And, as shown in FIG. 39, the metal film 60 covering the innerperipheral face of the seal portion 53 (the seal member 5 of rubber) maybe used instead of the metal thin plate 54 shown in FIG. 31. Accordingto this construction, carbon dioxide as the cooling medium gas in thehousing 31 is mostly shielded by the metal film 60, and leakage of thecooling medium gas is certainly limited to be small. Further,sealability at the sliding portion 52 is not spoiled because theelasticity (flexibility) of the lip end portion 13 b of the lip portion13 is not spoiled. And, the metal film 60 may be used instead of themetal thin plate 54 in FIG. 37 and FIG. 38.

[0211] And, the seal portion 53, covered with the gas shielding member51 such as the metal thin plate 54 and the metal film 60, is notrestricted to one construction as in the former embodiments. Forexample, surfaces of each of the two seal portions 53 may be coveredwith the gas shielding member 51. As shown in FIG. 40, for example, themetal thin plate 54 is fitted to the inner peripheral face of the sealmember 5 as the metal thin plate 54 works also as the supporting metal12, and the metal film 60 is formed on inner peripheral face of the(first) seal element 7. The both of the gas shielding members 51 may bethe metal thin plate 54 or the metal film 60. And, the gas shieldingmember 51 may be disposed on both sides of all of the seal portions 53to multi-shield the gas.

[0212] And, the metal thin plate 54 and the metal film 60 are notrestricted to fitting to the surface of the seal portion 53. Forexample, the metal thin plate 54 may be embedded in the seal portion 53.A seal portion 53 in which metal foil such as aluminum foil (or sheetmetal) is laminated is applicable. According to this construction,long-term reliability is secured because the metal foil is extendable tothe whole of the seal portion 53 in radial direction, and not worn outlike the metal foil 60 exposed on the surface. And, the metal foil doesnot spoil the elasticity of the seal portion 53 and the sealability atthe sliding portion of the seal portion 53.

[0213] And, material of the gas shielding member 51 is not restricted tometals. Any other materials, which can block the gas having highpermeability against the seal portion 53 of rubber or resin such ascarbon dioxide and ammonium, may be used. For example, ceramic may beused. In this case, it is preferable to form a ceramic film.

[0214] And, type of the rotation shaft seal is not restricted to theabove preferred embodiments. the seal element E may be composed of twoseal elements made of resin, and combined with a seal element made ofrubber. In this case, the gas shielding member 51 (the metal thin plate54 or the metal film 60) may be fitted to any of the three sealelements.

[0215] And, the rotation shaft seal may be applied to apparatuses otherthan a compressor.

[0216] In the present invention, not restricted to the above-describedpreferred embodiments, some of the individual constructions in the firstthrough the fifth preferred embodiments may be combined in various ways.

[0217] According to the rotation shaft seal of the present invention,excellent sealability and durability are demonstrated because thesupporting metal 12 tightly fits to and certainly supports the back faceof the seal member 5 of rubber to prevent the seal member 5 of rubberfrom being deformed in pressure reception, and, the slope receiving faceA tightly fits to and certainly holds the back face of the lip endportion 13 b to prevent the lip end portion 13 b from being deformed inpressure reception.

[0218] Especially, the contact area with which the end of the lip endportion 13 b slides on the rotation shaft 32 is prevented from increase,heat and abrasion are prevented, and life of the seal is extended.

[0219] And, for the high hardness of rubber, sealing ability anddurability are made better by synergistic effect with the supportingmetal 12.

[0220] Further, the end corner portion of the supporting metal 12 isprevented effectively from biting into the back face of the lip ndportion 13 b to cause fissures, and life of the seal member 5 isextended thereby.

[0221] And, according to the rotation shaft seal of the presentinvention, deformation of the lip end portion 13 b is reduced especiallyunder high pressure, because the lip end portion 13 b is reinforced bythe supporting metal 12 and the reinforcing cover metal 21, the tip endportion 14 linearly contact the rotation shaft 32 to secure highsealability, and abrasion of the lip portion is reduced to improvedurability.

[0222] And, in operation state in which pressure in the fluid storingchamber 33 is increased, the contact pressure of the lip end portion 13b to the rotation shaft 32 is decreased to reduce abrasion of the lipend portion 13 b.

[0223] Especially, the contact pressure with which the end of the lipend portion 13 b slides on the rotation shaft 32 is prevented fromincrease, heat and abrasion are prevented, and life of the seal isextended.

[0224] And, in operation state in which pressure in the fluid storingchamber 33 is increased, the seal has excellent durability with whichfissures on the root of the lip portion 13 and exfoliation (ofadherence) of the seal member 5 of rubber (the inner brim cover portion5 b) from the outer case 1 (the inner brim portion 2) are hardlygenerated.

[0225] And, the contact pressure of the lip end portion 13 b to therotation shaft 32 is decreased further to reduce the abrasion of the lipend portion 13 b.

[0226] And, according to the rotation shaft seal of the presentinvention, the force working on the rotation shaft 32 in the pressurizedstate of the fluid storing chamber 33 becomes small and abrasion of thelip end portion 13 b is reduced because tightening force is notgenerated (or slightly generated) when the seal is attached to therotation shaft 32 (in unpressurized state).

[0227] Especially, the contact area with which the lip end portion 13 bslides on the rotation shaft 32 is prevented from increase, heat andabrasion are prevented, and life of the seal is extended. And this ispreferable for an operational condition in which the pressure in thefluid storing chamber 33 is always positive.

[0228] Further, according to the rotation shaft seal of the presentinvention, high sealability against gas highly permeative through thematerial of the seal portion 53 is obtained because the gas is mostlyshielded by the gas shielding member 51 fitting to at least one sealmember 53 almost entirely in radial direction.

[0229] And, gas leakage is reduced by blocking the passage of gas withtwo seal portions 53 sandwiching the gas shielding member 51 to restrictthe gap.

[0230] Further, it is needless to treat the seal portion 53 withlaborious treatment such as film forming because the gas shieldingmember 51 is a metal plate (the metal thin plate 54), and theconfiguration of the seal member 53 is kept by holding the seal portion53.

[0231] And, according to the rotation shaft seal of the presentinvention, the elasticity (flexibility) of the seal portion 53 is hardlyspoiled because the gas shielding member 51 of which material is metal,ceramic, etc. is a shielding film covering the seal portion 53, andsealability of the seal portion 53 to the peripheral face of therotation shaft 32 at the sliding portions 52 and 59 is secured.

[0232] And, it is relatively easy to form the film technically and highrestricting ability against the gas permeation is obtained because theshielding film is the metal film 60.

[0233] Further, it is needless to treat the seal portion 53 withlaborious treatment such as film forming because the gas shieldingmember 51 is the supporting member 12, and the configuration of the sealportion 53 is kept by holding the seal portion 53.

[0234] While preferred embodiments of the present invention have beendescribed in this specification, it is to be understood that theinvention is illustrative and not restrictive, because various changesare possible within the spirit and indispensable features.

What is claimed is:
 1. A rotation shaft seal provided with a sealelement, which contacts a rotation shaft, disposed between a housing andthe rotation shaft, and a seal member of rubber having a lip end portionwhich contacts the rotation shaft and disposed on a fluid storingchamber side to the seal element, comprising a construction in which thelip end portion has a predetermined inclination angle to an axis of therotation shaft, a supporting metal, having a slope receiving faceforming the predetermined inclination angle with the axis of therotation shaft, contacts and directly supports a back face of the lipend portion gradually decreasing in diameter to the fluid storingchamber side.
 2. The rotation shaft seal as set forth in claim 1,wherein an hardness of the lip end portion of rubber is set to be 87 to96 in JIS.
 3. A rotation shaft seal provided with a seal element, whichcontacts a rotation shaft, disposed between a housing and the rotationshaft, and a seal member of rubber having a lip end portion whichcontacts the rotation shaft and disposed on a fluid storing chamber sideto the seal element, comprising a construction in which an innerperipheral face of the lip end portion is supported by a supportingmetal disposed between the seal element and the seal member, areinforcing cover metal is attached to a peripheral face of the lip endportion, and the lip end portion is sandwiched and held by thesupporting metal and the reinforcing cover metal.
 4. A rotation shaftseal provided with a seal element, which contacts a rotation shaft,disposed between a housing and the rotation shaft, and a lip endportion, which contacts the rotation shaft, disposed on a fluid storingchamber side to the seal element, comprising an end corner position ofthe lip end portion which linearly contacts or slightly parts from therotation shaft without interference in an unpressurized state, andcontacts the rotation shaft in a pressurized state of the fluid storingchamber.
 5. The rotation shaft seal as set forth in claim 4, wherein thelip end portion has a predetermined inclination angle to an axis of therotation shaft, and a supporting metal, having a slop receiving faceforming the predetermined inclination angle with the axis of therotation shaft, supports a back face of the lip end portion graduallydecreasing in diameter to the fluid storing chamber side.
 6. Therotation shaft as set forth in claim 5, wherein the predeterminedinclination angle is 10° to 45°.
 7. A rotation shaft seal provided witha seal portion of ring to prevent fluid leakage along a peripheral faceof a rotation shaft by a sliding portion of the seal portion sliding ona peripheral face of the rotation shaft, comprising anelastically-deformable gas shielding member made of a shielding filmcovering the seal portion which is fitted to the seal portion except thesliding portion and shielding gas until near the sliding portion.
 8. Arotation shaft seal provided with plural seal portions of ring toprevent fluid leakage along a peripheral face of a rotation shaft bysliding portions of the seal portions sliding on a peripheral face ofthe rotation shaft, comprising an elastically-deformable gas shieldingmember made of a shielding film covering the seal portion which isfitted to at least one of the seal portions except the sliding portionsand shielding gas until near the sliding portions.
 9. A rotation shaftseal provided with a seal element, disposed between a housing and therotation shaft, having a sliding portion which slides on a rotationshaft, and a seal member of rubber having a lip end portion providedwith a sliding portion which slides on the rotation shaft and disposedon a fluid storing chamber side to the seal element, comprising a gasshielding member, which can deform elastically with and keep fitted tothe seal element, is fitted to the seal portion except the slidingportions, and the seal member having a cylindrical cover portion whoseperipheral face is formed undulate in a free state to elasticallycontact an inner peripheral face of the housing for seal operation. 10.The rotation shaft seal as set forth in claim 1 or 3, wherein thesupporting metal is a gas shielding member.
 11. A rotation shaft sealprovided with a seal element, which contacts a rotation shaft, disposedbetween a housing and the rotation shaft, and a lip end portion, whichcontacts the rotation shaft, disposed on a fluid storing chamber side tothe seal element, comprising an end corner portion of the lip endportion which linearly contacts or slightly parts from the rotationshaft without interference in an unpressurized state, and contacts therotation shaft in a pressurized state of the fluid storing chamber, andthe seal member having a cylindrical cover portion whose peripheral faceis formed undulate in a free state to elastrically contact an innerperipheral face of the housing for seal operation.
 12. A rotation shaftseal provided with a seal element, which contacts a rotation shaft,disposed between a housing and the rotation shaft, and a lip endportion, which contacts the rotation shaft, disposed on a fluid storingchamber side to the seal element, comprising a supporting metal whichcontacts and supports directly a back face of the lip end portion, andan end corner portion of the lip end portion which linearly contacts orslightly parts from the rotation shaft without interference in anunpressurized state, and contacts the rotation shaft in a pressurizedstate of the fluid storing chamber.
 13. The rotation shaft seal as setforth in claim 11 or 12, wherein the lip end portion has a predeterminedinclination angle to an axis of the rotation shaft, and a supportingmetal, having a slope receiving face forming the predeterminedinclination angle with the axis of the rotation shaft, supports a backface of the lip end portion gradually decreasing in diameter to thefluid storing chamber side.
 14. The rotation shaft seal as set forth inclaim 13, wherein the predetermined inclination angle is 10° to 45°. 15.A rotation shaft seal provided with a seal portion of ring to preventfluid leakage along a peripheral face of a rotation shaft by a slidingportion of the seal portion sliding on a peripheral face of the rotationshaft, comprising an elastically-deformable gas shielding member made ofa metal film covering the seal portion which is fitted to the sealportion except the sliding portion and shielding gas until near thesliding portion.
 16. A rotation shaft seal provided with plural sealportions of ring to prevent fluid leakage along a peripheral face of arotation shaft by sliding portions of the seal portions sliding on aperipheral face of the rotation shaft, comprising anelastically-deformable gas shielding member made of a metal filmcovering the seal portion which is fitted to at least one of the sealportions except the sliding portions and shielding gas until near thesliding portions.
 17. A rotation shaft seal provided with a sealelement, disposed between a housing and the rotation shaft, having asliding portion which slides on a rotation shaft, and a seal member ofrubber having a lip end portion provided with a sliding portion whichslides on the rotation shaft and disposed on a fluid storing chamberside to the seal element, comprising a gas shielding member made of ashielding film, which can deform elastically with and keep fitted to theseal element or the seal member of rubber as a seal portion, is fittedto the seal portion except the sliding portions.
 18. A rotation shaftseal provided with a seal element, disposed between a housing and therotation shaft, having a sliding portion which slides on a rotationshaft, and a seal member of rubber having a lip end portion providedwith a sliding portion which slides on the rotation shaft and disposedon a fluid storing chamber side to the seal element, comprising a gasshielding member made of a metal film, which can deform elastically withand keep fitted to the seal element or the seal member of rubber as aseal portion, is fitted to the seal portion except the sliding portions.